How to "activate" some camera, i.e. view through it?
Ctrl+Numpad 0 sets an object as an active camera, but is not intended to change the point of view itself.
In order to view from the active camera, just press Numpad 0 or on the 3D Viewport's menu choose  View&gt; Viewpoint &gt; Camera.
Or select View &gt; Cameras &gt; Active Camera